1. Field of the Invention
The present invention relates generally to solar cells, and more particularly but not exclusively to back side contact solar cell structures and fabrication processes.
2. Description of the Background Art
Solar cells are well known devices for converting solar radiation to electrical energy. They may be fabricated on a semiconductor wafer using semiconductor processing technology. Generally speaking, a solar cell may be fabricated by forming p-type regions and n-type regions in a silicon substrate. Each adjacent p-type region and n-type region forms a p-n junction. Solar radiation impinging on the solar cell creates electrons and holes that migrate to the p-type and n-type regions, thereby creating voltage differentials across the p-n junctions. In a back side contact solar cell, the p-type and n-type regions are coupled to metal contacts on the back side of the solar cell to allow an external electrical circuit or device to be coupled to and be powered by the solar cell. Back side contact solar cells are also disclosed in U.S. Pat. Nos. 5,053,083 and 4,927,770, which are both incorporated herein by reference in their entirety.
The conversion efficiency of a solar cell is a measure of how much electrical power the solar cell generates relative to received solar radiation. Although currently available solar cells are very efficient, even more efficient solar cells are required to meet future demands for renewable energy sources.